Exploring Novel Electronic Structures of Topological Quantum Matter

探索拓扑量子物质的新型电子结构

• 批准号: EP/K04074X/1
• 负责人: Yulin Chen
• 金额: $ 12.73万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK04074X%2F1
• 关键词: Exploring; Novel; Electronic; Structures; Topological

Electronic materials play a tremendous role in almost every aspect of modern life - from supercomputers to household electronics - and the behavior of electrons in these materials determines their rich and unusual properties. Historically, the discoveries of novel electronic quantum materials have caused revolutions in our lifestyle and economy, such as the discovery of semiconductors. Very recently, an entirely new type of electronic materials, the topological insulator, was theoretically predicted and experimentally realized.Topological insulators represent a brand new state of quantum matter that is distinct to ALL previously known states. On the face of it, they are well-known, off the shelf materials; but they have profound, yet previously overlooked properties that make them so unique. In its pure form, a topological insulator has a full energy gap in the bulk electron band (thus like an insulator); while on the surface, it has metallic states formed by electrons with linear energy-momentum relationship (similar to photons that do not possess rest mass!) with their spin polarization completely determined by their moving directions. More dramatically, these unusual electrons are extremely robust, and can flow on the surface of topological insulators against any non-magnetic impurities, crystalline defects or surface distortions. Due to the great scientific significance and technological potential, topological insulators have grown as one of the most intensely studied fields in condensed matter physics within the last few years.However, while the scientists worldwide are advancing the frontier of this exciting field, there remain many challenges before we can actually realize the many amazing quantum phenomena (such as the magnetic monopoles, half electron charge and many topological magneto-electric effects resulted from the revised Maxwell equations in topological insulators) and practical applications (such as novel electronic, spintronic and thermoelectric applications) topological insulators promise. For examples, current topological insulators typically have excessive bulk carriers, thus prevent the bulk from being insulating (which will mask the subtle topological effects from the surface electrons); and the small bulk energy gap also prevent them from being used in high (room) temperature electronic devices. Thus we would like to solve these problems by carrying out this project to improve the quality of current topological insulators, and search for even better topological insulators with larger bulk energy gap and more stable in regular environments. We will also explore the pathways to use the unusual electronic and spin properties of topological insulators in practical applications, such as ultra-low power electronics, novel spintronic devices, optoelectronic applications, high efficiency thermoelectric applications and catalysis applications.Furthermore, the swift development of topological insulators has also inspired the study of other new topological states, such as quantum anomalous Hall insulators, topological semi-metals, topological crystalline insulators and topological superconductors, etc. These new topological states will unlock the door to even richer exotic quantum phenomena (such as quantized Hall conductance without externally applied magnetic field, and the exotic Majorana fermions that are their own anti-particles) and more unconventional applications (from ultra-low integrate circuit to future topological quantum computers) Thus we will also search for these novel phases of quantum matter in this project.

电子材料在现代生活的几乎方方面面--从超级计算机到家用电子产品--都发挥着巨大的作用，而这些材料中电子的行为决定了它们丰富而不同寻常的性质。从历史上看，新型电子量子材料的发现给我们的生活方式和经济带来了革命，比如半导体的发现。最近，一种全新的电子材料--拓扑绝缘体被从理论上预测并在实验上实现。拓扑绝缘体代表了一种全新的量子物质状态，它与所有已知的状态都不同。从表面上看，它们是众所周知的现成材料；但它们具有深刻但以前被忽视的特性，使它们如此独特。在其纯形式中，拓扑绝缘体在体电子能带中具有全能隙(因此类似于绝缘体)；而在表面上，它具有由具有线性能量-动量关系的电子形成的金属态(类似于不具有静止质量的光子！)它们的自旋极化完全由它们的运动方向决定。更戏剧性的是，这些不寻常的电子非常健壮，可以在拓扑绝缘体表面流动，抵御任何非磁性杂质、晶体缺陷或表面扭曲。由于其巨大的科学意义和技术潜力，近几年来，拓扑绝缘体已经成为凝聚态物理中最热门的研究领域之一。然而，尽管世界各地的科学家们都在这一令人兴奋的领域取得进展，但在我们真正实现许多令人惊叹的量子现象(如修正的麦克斯韦方程所产生的磁单极子、半电子电荷和许多拓扑磁电效应)和实际应用(如新颖的电子、自旋电子和热电应用)之前，拓扑绝缘体仍然存在许多挑战。例如，目前的拓扑绝缘体通常具有过多的体载流子，因此阻止了体载流子的绝缘(这将掩盖表面电子的微妙拓扑效应)；较小的体能隙也阻止了它们被用于高温(室温)电子器件。因此，我们想通过开展这一项目来解决这些问题，以提高现有的拓扑绝缘子的质量，并寻找更好的拓扑绝缘子，使其具有更大的体积能隙，在规则的环境中更稳定。我们还将探索拓扑绝缘体的特殊电子和自旋性质在实际应用中的途径，如超低功率电子学、新型自旋电子器件、光电应用、高效热电应用和催化应用。此外，拓扑绝缘体的快速发展也启发了对其他新拓扑态的研究，如量子反常霍尔绝缘体、拓扑半金属、拓扑晶体绝缘体和拓扑超导体等。这些新的拓扑态将打开更丰富的奇异量子现象的大门(如量子化的霍尔电导在没有外加磁场的情况下，以及奇异的Majorana费米子(它们本身就是反粒子)和更多的非常规应用(从超低集成电路到未来的拓扑量子计算机)，因此我们也将在这个项目中寻找这些新的量子物质相。

项目成果

Single crystalline electronic structure and growth mechanism of aligned square graphene sheets

• DOI: 10.1063/1.5012947
• 发表时间: 2018-03
• 期刊: APL Materials
• 影响因子: 6.1
• 作者: Haifeng Yang;Changkang Chen;Huan Wang;Zhongkai Liu;T. Zhang;Han Peng;N. B. M. Schröter;S. Ekahana;Juan Jiang;L. Yang;V. Kandyba;A. Barinov;Chaoyu Chen;J. Avila;M. Asensio;H. Peng;Zhongfan Liu;Yulin Chen

Linear magnetoresistance caused by mobility fluctuations in the n-doped Cd3As2

n 掺杂 Cd3As2 迁移率波动引起的线性磁阻

• DOI: 10.48550/arxiv.1412.4105
• 发表时间: 2014
• 作者: Narayanan A

Emergence of the nematic electronic state in FeSe

FeSe 中向列电子态的出现

• DOI: 10.48550/arxiv.1502.02917
• 发表时间: 2015
• 作者: Watson M

Extremely large magnetoresistance and ultrahigh mobility in the topological Weyl semimetal candidate NbP

• DOI: 10.1038/nphys3372
• 发表时间: 2015-08-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Shekhar, Chandra;Nayak, Ajaya K.;Yan, Binghai
• 通讯作者: Yan, Binghai

Discovery of a single topological Dirac fermion in the strong inversion asymmetric compound BiTeCl

• DOI: 10.1038/nphys2768
• 发表时间: 2013-11-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Chen, Y. L.;Kanou, M.;Sasagawa, T.
• 通讯作者: Sasagawa, T.